1. Field of the Invention
The present invention relates to a micro vapor chamber, and in particular to a micro vapor chamber in which a condensing region is provided with protrusions for allowing condensed working fluid to be quickly collected thereon so as to accelerate the flowing of the condensed working fluid back to an evaporating region. By this structure, the efficiency of liquid-vapor phase circulation of the working fluid in the micro vapor chamber is improved greatly.
2. Description of Prior Art
Currently, electronic apparatuses are gradually made to be more and more compact. Although the dimension of a semiconductor forming an electronic element is reduced, the performance of the semiconductor and the formed electronic element has to be increased. However, the increased performance of the electronic element inevitably generates more heat during its operation. Thus, it is an important issue to dissipate the heat generated by the electronic apparatus or system in order to improve its performance.
When the size of a semiconductor is reduced, its heat flux is increased. The increase in heat flux may cause a challenge to the cooling of an electronic product and make the electronic elements to be overheated at different times and locations. As a result, the electronic elements of the electronic product may suffer damage or break down.
Conventionally, in order to solve the problem of small space for heat dissipation, a vapor chamber is proposed, which is disposed above a chip (heat-generating element) as a heat sink. In order to increase the capillary force, a wick structure made of coated copper posts, sintered posts, foamed posts or the like is supported in the vapor chamber. Channels among these posts are used as reflow channels for allowing the working fluid condensed at a condensing region of the vapor chamber to flow back to an evaporating region of the vapor chamber. However, since the thickness of upper and lower walls of a micro vapor chamber is small (<1.5 mm), the portions of the above-mentioned micro vapor chamber in which no copper posts, sintered posts or foamed posts are supported may collapse or cave. As a result, the flatness and strength of the micro vapor chamber cannot be maintained in an ideal value, which makes the compact design of the micro vapor chamber difficult.
In the above-mentioned vapor chamber, the working fluid is heated in the evaporating region to evaporate, whereby the working fluid transforms from liquid phase into vapor phase. The vapor-phase working fluid is condensed in the condensing region, whereby the working fluid transforms from vapor phase into liquid phase and flows back to the evaporating region for circulation. The condensing region of the vapor chamber is usually formed into a smooth surface or a sintered wick structure, so that the droplets of the working fluid condensed in the condensing region can flow back to the evaporating region by means of gravity force or the capillary force generated by the wick structure. However, since the condensing region is formed into a smooth surface, the condensed droplet of the working fluid has to be collected to a volume large enough to drip down by gravity force. Thus, the reflow rate of the working fluid is insufficient. On the other hand, since the reflow rate of the working fluid is small, the working fluid may dry out in the evaporating region to greatly deteriorate the thermal-conducting efficiency of the whole vapor chamber. If the number or density of the wick structure (either made of sintered posts or meshes) is increased to improve the reflow rate of the working fluid, such a sintered or meshed wick structure will make the vapor chamber unable to be further compact.
Therefore, the conventional vapor chamber has the following problems:
(1) the reflow rate of the working fluid is too slow;
(2) its thermal-conducting efficiency is poor; and
(3) the compact design thereof is difficult.